Several high tech applications depend on light sources and highly sophisticated optical systems for their primary process. For instance, in the semiconductor industry, the new generation lithography tools employ high power lasers for generation of EUV exposure light, while in the space industry high power lasers are used to create laser guide stars. Also in material processing and machining, lasers are applied for local melting, or cutting through raw material.
A driving trend that is shared among the associated application roadmaps is towards increasing power of the light being processed combined with tightening optical requirements.
This poses new technological challenges, since performance of the optical systems is highly dependent on the accuracy and stability of the optical elements in the light processing path. Raising the light source power levels impose increasing threats, e.g. through extreme thermal loading that may lead to deformations of optical surfaces and thus causing optical performance deteriorations such as focus shift which directly impact the primary process and performance.
The most promising solution directions lies in the field of Adaptive Optics (AO), where active control is introduced in the light processing system to preserve or adapt the shape of optical elements, such that optical performance is continuously guaranteed and disturbance influences are being suppressed. Adaptive Optics has proven its merits already in various high performance applications, such as deformable mirrors in astronomy instruments. A challenge that is apparent here is to make adaptive optics also available to high power applications as well.
Likewise, in space industry as well, adequate adaptive optics for high power lasers would be of benefit in creating brighter and more stable guide stars.
In particular, the present invention relates to a deformable reflective structure that can be used in an optical device to dynamically transform the wavefront of a light beam.
However, current deformable reflectors are not capable of handling high power light beams.
One of the other key challenges in the development of a deformable mirror is the small actuator pitch in combination with a large inter-actuator stroke on a continuous face sheet.
A further object of the present invention is to provide a deformable reflective structure that is easily scalable in diameter from several millimetres to tens of centimetres.
A further object of the present invention is to provide a deformable reflective structure that is easy to produce on an industrial scale, at competitive costs.
US2010/078543 shows a pressure environment for a flexible membrane active on both sides. The environment is sealed by a transparent conductor designed to pull up the membrane in order to maintain a flat shape. However this provision necessarily impedes the light transmission to the membrane.